Process of producing coke



R. P. PERRY PROCESS OF PRODUCING COKE Oct. 7 1924. 1,511,192

Filed Dec. 10 1919 INVENTOR ATTORNEY Patented Oct. 7, 1924;.

UNITED STATES PATENT OFFICE.

RAY P. PERRY, OF UPPER MONTCLAIR, NEW JERSEY, ASSIGNOR TO THE BARRETT COMPANY, A CORPORATION OF NEW JERSEY.

PROCESS OF PRODUCING COKE.

Application filed December 10, 1919.

To all whom it may concern Be it known that I, RAY P. PERRY, a citizen of the United States, residing at Upper Montclai'r, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Processes of Producing Coke, of which the following is a specification.

This invention relates to the production ofcoke. It relates more particularly to the production of .coke from coal tar or coal tar residues or pitches.

' In this application the term coal tar is used to include the different varieties of coal tar, such as gas works coal tar and by-product coke oven tan-water gas tar, etc.

i For a long time it has been known that coke could be obtained by the destructive distillation of coaltar, the characteristics and quality of the coke depending largely upon the sort of coal tar used. It has also been known that coke could be obtained from coal tar by first distilling off the lighter or more volatile constituents in order to obtain a residue commonly known as pitch, and then coking the pitch. This residue or pitch is usually coked by being introduced into a separate still where it is subjected to the coking operation whereby the coke is produced.

In the prior processes of producing coke from coal tar pitch it has been necessary to provide a still or retort or oven of such capacity that it is only partially filled with the pitch to be coked. This necessity arises from the fact-that pitches obtained from coal tar are of such a nature or contain a certain amount of constituents of such a nature that considerable foaming of the mass will be caused while the coking operation is taking place thus often causing the mass to overflow so as to mix with and contaminate the distillates, besides resulting in the loss of material and interfering with the operation of the-apparatus. To avoid this foaming over it is often necessary to limit the quantity of pitch charged into the coking vessel so that it is only about half full or even less.

' The object of this invention is to overcome these difficulties and to produce coke from coal tar or pitch without endangering the apparatus or wasting the materials. In carrying out the invention coal tar is first distilled preferably while simultaneously Serial No. 343,717.

circulating through it an inert insoluble gas which will cause the volatile constituents to pass off at a lower temperature than would be required in the usual processes and, at the same time, will result in the production of an appreciably smaller amount of free carbon in the residue or pitch. The pitch produced by the aid of the recirculating gas of the character mentioned can be made to have a very much higher melting point than that ordinarily produced.

The gas used for recirculation should preferably be permanent at ordinary temperatures, should not act chemically upon the tar and should be practically insoluble in the tar. Nitrogen, carbon dioxide, and carbon monoxide have been found to be suitable for this purpose. In this way pitch may be obtained which has a melting point of 450 F; or higher.

It has been found by repeated trials that when pitch having a melting point or about 450 F. or higher is subjected to coking operation in a still no objectionable foaming takes place, but that the distillates pass off quietly when heat is applied and the Coke is formed without great swelling of the mass so that the coking still can be charged to substantially its full capacity thus saving in equipment and attendants.

The tendency of hitherto known pitches of 400 F. melting point or less to swell or foam during the coking of the same does not seem to depend entirely upon their melting points since some pitches of certain melting points have been found to foam worse during the coking process than others of lower melting points While the converse is true with many other pitches. While not desiring to commit myself to any particular theory as to the cause of the absence of objectionable foaming when pitch is coked which has been produced by distilling tar with the aid of recirculating gases, it is suggested that the foam creating constituents, which are present in the pitches produced in the ordinary way without gas recirculation, are removed by the gas recirculation when the distillation has been carried far enough so that the pitch cannot be made to foam during the coking operation, or at least does not foam appreci-' ably during the coking process. With the pitches obtained from commercial coal tar there seems to be a somewhat clearly fixed point of demarkation between pitches which ber of tests have indicated that pitches having a melting point below-an approximate temperature of 400 F. give rise to an objectionableamount of foaming when they are coked While those of higher melting points show a surprising and marked improvement in this respect. The melting points are to be determined by the cube in air method as I described on page 821 of Vol. 10 of the Journal of Industrial and Engineering Chemistry.

The invention will be understood from the description in connection with the drawing which is a diagrammatic representation of an arrangement of apparatus for carrying out the process.

In' the drawing reference character 1 refers to a still for coal tar which is provided with an inlet pipe 2 for coal tar from a source (not shown) and an outlet pipe 3 provided with a valve 4 for the hot residue or pitch. Heating means for the still 1 are shown at 5.

A circulation system for the inert gases is shown as consisting of an arrangement including a perforated pipe 6 extending near the bottom ofstill 1 through which the gases pass and after bubbling through the tar in still 1 pass to the outlet pipe 7 for the gases to the condenser 8 and through pipe 9 to pump 10 and back to pipe6.

The hot liquid residue or pitch of nonfcaming character resulting from the distillation in tank 1 with gas recirculation is preferably transferred in liquid form through pipe 3 to still or retort 11 where the coking operation takes place at a temperature of about 700 F. or higher, while the distillates from the pitch during the coking operation pass out through outlet pipe 12. Heating means 13 are shown for the still 11, and the coke is withdrawn from the still 11 in the usual manner when the coking operation has been completed. Instead of charging the liquid pitch into the coking still or retort it may be first cooled or solidified and charged in solid pieces into the coking still or retort but generally it is desired to save time and heat by charging the pitch in hot liquid form.

I claim 1. The herein described process which comprises distilling coal tar while circulating a neutral gas therethrough until a pitch residue is produced which will not foam appreciably when subjected to a coking temperature, and coking said residue.

2. The herein described process which comprises distilling coal tar while circulating a neutral gas therethrough until a pitch residue is produced which has a melting point above 400 F., and coking said residue.

3. The process which comprises cokin pitch of a'melting point of about 450 which has been produced by distillation of coal-tar while circulating a neutral gas therethrough by subjecting it to a high temperature.

In testimony whereof I aifiz; my signature.

RAY P. PERRY. 

